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Abuse may trigger gene changes found in suicide victims

By Alison Motluk

Early child abuse may forever change the way genes are expressed in the brain, suggests a postmortem study of people who died by suicide.

It is now well established that it isn’t just what genes we inherit, but how they are turned on and off that influences our development. Most of these control switches are thrown before we are born, but some are set in early life, and to a lesser degree, throughout our lives.

Genes are switched off when methyl groups are added to our DNA. Studies have shown that diet, stress and even maternal care can influence these “epigenetic” changes.

Care factor

In 2004, for instance, Moshe Szyf and his colleagues at McGill University in Montreal showed that rat pups neglected by their mothers had different levels of methylation and different stress responses from those that were well-cared for. They also showed that, with careful interventions, this could be reversed.

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Could early care in humans also affect methylation levels?

Szyf knew that a sizable proportion of people who commit suicide were abused or neglected early in life. So his team examined the brains of 13 suicide victims who had a history of early neglect or abuse, and compared them to 11 age and gender matched controls, who had had normal upbringings but had died in sudden accidents.

The researchers were especially interested in a part of the brain called the hippocampus, which is involved in memory and mood, and is known to be smaller in people who have suffered abuse.

They examined genes in the hippocampus involved in controlling protein-producing RNA, and they found that in the suicide victims, a much higher proportion of these genes had been switched off, suggesting the hippocampus was indeed less active. This raises the question of whether epigenetic effects influence suicide risk.

Suicide intervention

Szyf thinks that the altered methylation is the result of child abuse and not suicide itself, and is now studying suicide victims who have not suffered abuse to confirm this.

He is ultimately interested in finding a way to undo these epigenetic changes. “The question is whether we could design an intervention – dietary, social, pharmacological – that could reverse it,” says Szyf.

“I think it’s very provocative,” says Arthur Beaudet at Baylor College of Medicine in Houston, Texas. “There’s going to be a lot of heterogeneity in people who commit suicide. The fact that you find anything at all makes it interesting.” He would like to see the work replicated, however.

“It’s an important piece of work,” says Craig Cooney at the University of Arkansas in Little Rock. “It points the way toward possible diagnosis and intervention.”